O10.42 Pre-existing secondary hypertension complicating childbirth

Billable ICD-10-CM code, FY2026. Acts as a Major Complication or Comorbidity (MCC) as a secondary diagnosis.

Applies from O10 Pre-existing hypertension complicating pregnancy, childbirth and the puerperium

Includes

• pre-existing hypertension with pre-existing proteinuria complicating pregnancy, childbirth and the puerperium

Excludes2 (not included here)

• pre-existing hypertension with superimposed pre-eclampsia complicating pregnancy, childbirth and the puerperium (O11.-)

Applies from O10.4 Pre-existing secondary hypertension complicating pregnancy, childbirth and the puerperium

Applicable to

• Any condition in I15 specified as a reason for obstetric care during pregnancy, childbirth or the puerperium

Use additional code

• code from I15 to identify the type of secondary hypertension

MS-DRG index

Defines the logic of DRG(s) 998 in MDC 14.

Approximate ICD-9-CM (GEMs)

• 642.11 Hypertension secondary to renal disease, complicating pregnancy, childbirth, and the puerperium, delivered, with or without mention of antepartum condition (approximate)

Medicare Code Edits (MCE v43.1 (April 2026))

• Maternity diagnoses (age 9 through 64): Age conflict edit. These diagnoses are clinically expected only in patients age 9 through 64.

Code annotations containing back-references to O10.42

Back-references to O10

• Type 1 Excludes: I10 Essential (primary) hypertension ("hypertensive disease complicating pregnancy, childbirth and the puerperium (O10-O11, O13-O16)")
• Use Additional: O11 Pre-existing hypertension with pre-eclampsia ("code from O10 to identify the type of hypertension")
• Type 2 Excludes: O99.4 Diseases of the circulatory system complicating pregnancy, childbirth and the puerperium ("hypertensive disorders (O10-O16)")

Diagnosis Index entries for O10.42

• Hypertension, hypertensive (accelerated) (benign) (essential) (idiopathic) (malignant) (systemic) › complicating › childbirth (labor) › secondary

Nearby codes

• O10.41 Pre-existing secondary hypertension complicating pregnancy
• O10.411 Pre-existing secondary hypertension complicating pregnancy, first trimester
• O10.412 Pre-existing secondary hypertension complicating pregnancy, second trimester
• O10.413 Pre-existing secondary hypertension complicating pregnancy, third trimester
• O10.419 Pre-existing secondary hypertension complicating pregnancy, unspecified trimester
• O10.42 Pre-existing secondary hypertension complicating childbirth (this code)
• O10.43 Pre-existing secondary hypertension complicating the puerperium
• O10.9 Unspecified pre-existing hypertension complicating pregnancy, childbirth and the puerperium
• O10.91 Unspecified pre-existing hypertension complicating pregnancy
• O10.911 Unspecified pre-existing hypertension complicating pregnancy, first trimester
• O10.912 Unspecified pre-existing hypertension complicating pregnancy, second trimester